Manifold injection carburetor



Au@ 14, 1945- o. L GARRE-rsoN MANIFOLD INJECTION CARBURETOR Filed Hatch19, 1942 lla mvENToR owen LfGARREr N A mi I l f.. v lMB/Y.

Patented Aug. .l4, 1945 2,382,625 MANIIFOLD NJECTN 'CARBURETOR Owen L..Garretsom Detroit, Mich., as'sgnor to Phillips Petroleum Company, acorporation of Delaware a i siam.

' invention relates to a method of fuel injeci tion in internalcombustion engines; and to appalresortto positive displacementpiston-type injectors which' are common to pastI devices. The

yuse of c-operated injector pumps |in previous devices has required amodification of the structure of the engine promr, whereas my device maybe applied to the manifold of any standard gas engine. My device has afurther advantage over conventional charge-forming devices in that theVenturi tube and the main th'rottle valve are the only major parts whichneed be attaoh'ed directly to the engine manifold. All the fuel controlelefments may be placed at a reasonably remote point by suitableextension of the tubing connections leading to the engine manifold.VThus, all the adinstable moving par-ts, exceptthe throttle itself, maybe placed wherever they will -be most accessible for adjustment orrepair. f5

My invention has for its main objectv the ac-v complishment of directfuel injection to the var'- ious manifold branchesof a gas engine bymeans directly controlled bythe engine air intake.

It is a further object to attain the above 'function with the minimum ofparts and at the least expense of manufacture.

vAnother object is to provide the inherent ad- .vantages ofldirectmanifold-injection in an embodiment which lcan be applied V4to standard;en gines without modification of the latter. An important object is topermit installation of the fuel control device at an accessiblelocation,

, In the drawing, the numeral I denotes the intake manifold riser of aninternal combustion engine in which the branches 2 are provided for`distribution of air and fuel to the various cylinders of the engine inthe customary manner. In mydevice, however, the fuel is introduced bymeans of individual nozzles 3, located in each of the aforementionedbranches, the nozzles receiving their fuel Vthrough branches emanatingfrom a common fuel line 4.

The flow of fuel in the line 4 is controlled by the' fuel governorindicated 'generally by the numeral 5, fuel being conducted to thelatter, under pressure, through' the inlet line 6 from the supply source(not shown). x

The fuel governor has the upper and lower diaphragms l and 8,respectively, which are mounted on a common sterir 9, and attached tothe latter part is a valve disc I0 whichis thus responsive to the motionof the two diaphragms. `By virtue of theJ two diaphragms, the upperportion of the fuel governor is divided into two chambers I I and I2;the lower portion is likewise divided into two 'chambers I3 and I4. Abushing I5 is pressed into the structure so as to separate the chamberI2 fromgchamber I3, and is provided with an opening to receive the stem9, This opening is reamed l to a close yfit with the stem, the clearancebeing lnozzle I 6 for'the valve disc I0, whichI together form athrottling valve controlling the fuel ow.

' The vupperend of the nozzle `channel is restricted so as to formaguide I 'I for the valve stem 9. This guide serves only 'to center thedisc II) coaxially with respect to the nozzle I6, and has nopressurewhereas other devices must practically always be mounteddirectly on th'e manifold intake riser, re

gardless loi the convenience.v or inconvenience of such a location It isalso an important obiect to permit -use of/a.

wide range fuels by simple adaptations of thejuel line pressure andmanifold Jet size to accommo- 'j este them.`

The advantages of positive pressure fuel iniection to an engine manifoldare per se well sealing function as in the case of the upper guide I5.One or more openings I8 `are provided to comthe upper end of the stem 9.In Itheform of known, and a complete recitation of them herewouldbesuperuous.

my device herein illustrated,- I prefer to use a tension spring here, inwhich case` the disc IIl would be urged toward the nozzle I6 and themainfucl, valve would thus be heldl closed when the engine is notrunning. -A screw I9 is provided for adjustment of the tension spring'.`Obviously the degree of tension or compression on spring I8A will dependon the particular installation and relative size of the diaphragms 'Iand 8.

A pressure conduit communicates from the chamber I3 to a point below themain throttle 2| in the manifold riser. A second pressure conduit 22communicates between chamber I2 and 'a restricted venturi section 23 inthe manifold riser. A third pressure conduit 24 connects the chamber IIto the riser I at a point on the air inlet side of the venturi. An idlefuel line 25 by-passes the main governor valve, and is fitted with anadjustable needle valve 26 In operation, liquid hydrocarbon fuel(preferably) is supplied under pressure through the line 6, the pressurebeing provided by an enginedriven fuel pump, or other means, not shown.Assuming the throttle II to be substantially closed and the enginerunning at idling speed, a high degree of suction will exist inline 20,and the pressure in lines,22 and 24 will be substantially atmospheric.As a result, the dominant force on the governor mechanism will be theupward-acting force on the lower diaphragm 8 due to the suction in line20 and chamber I3. Hence the valve I0 will be closed tightly, and fuelwill enter the engine manifold only by virtue of the by-pass line 25.The needle valve 26 is adjusted to pass the required fuel for goodengine idling.

Upon opening of the throttle, the pressure in line 20 and chamber I3will rise. At the same time, the flow of air will be accelerated throughthe venturi 23, and a suction will be induced in line 22 leading tochamber I2. A downward force will hence be generated on the largediaphragm l. This downward force, due to proper propor- -tioning ofsizes of the diaphragms, will begreat enough to overcome the nowdiminished upward force on diaphragm 8, resulting in opening of valve I0and an additional flow of fuel under pressure of the fuel pumpwill-occur through the line 4 and the nozzles 3. As valve`l0 opens, thepressure in chamber I4 increases to a. point sufequilibrium soestablished. The proper air fuel ratio at this running condition caneasily be -obtained by proper sizing of the jets 3, and a fineadjustment lis .also provided by the spring IBA and the screw I9. Havingonce established the proper relationship of diaphragm, main fuel valveand nozzle sizes, and having made the proper final adjustment of thespring, the maintenance of any desired constant air-fuel ratio isautomatic.'

, The quantity of air passing the throttle plate for'anv given degree ofopening is dependent upon the pressure differential across the throttle.Upon analysis of the above-described mode of operation of the fuelgovernor, it is obvious that the main fuel flow is also in proportion tothe same differential (i. e'. the difference in pressures in lines 20and 22), and hence the air-fuel ratio is maintained at a substantiallyconstant value so far as the main fuel is concern It is realized thatthe 'by-pass line 25 is not directly governed by the air differential,and may range of the engine, however, even the by-passed ,ficient tobalance the force system, and the valve g will come to a positiondetermined by the new` be in proportion to engine speed. Moreover, theby-pass line 25 could be eliminated by providing an adjustable stop onthe main fuel valve stem, so that it could always be maintainedsufficiently open to pass the required fuel for idling.

By proper design of the spring IIA, any desired air-fuel ratiocharacteristic can be developed. -For example, 'if a particular orificechosen for the fuel jet 3 had the characteristic of varying as tocoeillcient of flow discharge (as most orifices actually do), then theair-fuel ratio would be influenced accordingly at various engine speeds.By selecting a spring of proper rate, this. deviation from a constantmixture ratio could be modified to suit the requirement at hand. In manycases, a variation of mixture ratio is desired at different speeds.

Other possible modifications in the matter of fuel governing areobviously afforded by my device. The rate of response to varyingpressure conditions can be regulated by providing needle valves or otherrestrictions in the lines 20 and 22. Moreover, the pressure differentialbetween these two lines could be adjusted by connecting the linestogether at some point between the manifold riser and the governor andinstalling an adjustable restriction in the connecting line. Further,the distribution of fuel to the various cylinders can be compensated tosuit the manifold flow characteristics by Calibrating the fuel jets andthus obtaining perfect distribution of the total' fuel charge among thevarious cylinders. Pressure drop in the fuel line leading to the variousjets could be compensated in the same manner.

The line 24 is provided simply to insure that the top of the diaphragm'I will always be sublected to the inlet air pressure, and thus theeffect of air cleaner resistance or other disturbing influences will benullified. This line is desirable but not necessary tion.

It is to be understood that I do 'not limit my device to any particularfuel. High or low vapor pressure liquid fuels, or high pressure vapor--form fuels could be accommodated by proper proportloning of the fuelpressure, the diaphragms sizes, and the fuel valve and jet sizes. In thecase of low pressure liquid fuels, a fuel pump would serve to providethe injection pressure. In the case of high vapor pressure liquid orvapor fuels, a pressure reducing regulator could be made to serve inplace of th`e fuel pump. The

-only requirement vital to operation of the sysposition of theparticular fuel.

tem is that the fuel be supplied to the control I valve at a pressurehigh enough to afford control by throttlingthe `fuel pressure throughthe valve, and that the residual pressure after throttling will be highenough to afford positive injection into'the manifold.

1 There are of course certain additional requisites of a practicalnature. For example,'if liquid fuels are used, vapor lock must beprevented by maintaining the pressure on the fuel at a relatively highlevel, depending upon the com- Conversely, in

` using a vapor phase fuel, care must be taken to idling fuel will notdisturb the overall. air-fuel v ratio, since the airflow throughthe-manifold and the fuel flow through the line 25 will both.

avoid condensation of the vapor due to using fuel pressures in excess ofthe ldew point pressure at the lowest temperature to be encountered.

These are factors which can be controlled or of heat, etc. Therefinements necessary to prf.

'to the operation of my invenhousings being separated from each other,resil.

vide satisfactory operation will vary, therefore,v in accordance withthe fuel selected and the selection of the fuel and the rened form of mydevice are matters simply of engineering and mechanics. w

I recognize that my device is most easily adaptable to ordinary gasolinefed to the system by means of an engine-driven fuel pump, but this isonly a preferred adaptation, and other fuels are usable in view of thediscussion set forth above. r

I claim:

In a fuel system for an engine having an intake manifold, a source offuel under pressure,

Aa fuel supply pipe connecting said source with the intake manifold andyincluding at least one metering orifice opening into the manifold, anair inlet communicating with the intake manifold having a venturiand/throttle therein downstream of said venturi, the improvementcomprising a fuel control device including a valve in said supply pipecontrolling the ow of fuel to the intake manifold, said valve having astem connected to a lower diaphragm and an upper diaphragm, a iirst anda second housing. the upper diaphragm dividing the first housing intotwo chambers and the lower diaphragm dividing the second housing intotwo chambers, said lent means in the upper chamber of the first housingurging the valve closed, a pipe connecting the lower chamber of the-msthousing with the venturi section and being at the same pressure as theventuri section, a pipe connecting the upper chamber of the rst housingwith the air inlet pipe upstream of the venturi sec tion, the diaphragmof the iirst housing being responsive to suction induced by kincreased,air now through the venturi section which results in a higher pressurein the upper chamber oi the ilrst `housing' than'in the lower chamber ofthe rst housing to open the valve against the force of the resilientmeans, a pipe connectingthe'upper chamber of the second housing with theair inlet downstream of the throttle and said mf ber being undersuctiony upon decreased air now through the venturi by closing of thethrottle valve, the lower chamber of `the second housing communicating'with the fuel supply pipe when said valve is open, said resilient meansclosing said valve under the unstable conditions existing when thethrottle is in idling position, and a fuel idling connection around saidvalve to byfuelY from said source to said oriice when said valve isclosed. y

OWEN L.

